SOLVENT EFFECT ON PHOTOSENSITIZED OXIDATION OF IODIDE ION BY ANTHRACENE SULPHONATES

Abstract— Iodide ion oxidation by singlet oxygen is found to be influenced by two properties of the solvent. One is the polarity of the solvent and the other is the availability of protons in the solvent. By suitable choice of solvents and solvent mixtures both kinds of effects have been studied. In water-methanol mixtures the reaction is found to be facilitated in more polar medium. In isodielectric media as obtained by mixtures of acetonitrile and methanol the reaction is repressed with increase in the aprotic component (CH₃CN) in the solvent. The same effect is observed in the DMSO-H, O mixtures. In heavy water the reaction rate is doubled and the effect fits well into the proposed kinetic scheme involving singlet oxygen for photosensitized oxidation of I^- by anthracene sulphonates.